We seem to hear more and more about natural weather disasters – are these signs of global warming? 

Or do they just illustrate the unpredictability of the weather?

Luckily, Hurricane Gustav doesn’t seem to have inflicted devastation on the U.S. Gulf coast comparable to Katrina in 2005. On the other side of the world, the worst floods in India’s Bihar province in 50 years have displaced about three million people and killed at least 90.

Achim Steiner, head of the U.N. Environment Programme, says that more powerful hurricanes and more floods are in line with predictions by the U.N. Climate Panel of ever more disruptions linked to a build-up of greenhouse gases.   

The panel said in a 2007 report that global warming was already “unequivocal” and that it was at least 90 percent likely that human activities — led by burning fossil fuels — were the main cause of warming in the past 50 years.

It said observed shifts include “changes in arctic temperatures and ice, widespread changes in precipitation amounts, ocean salinity, wind patterns and aspects of extreme weather including droughts, heavy precipitation, heatwaves and the intensity of tropical cyclones.”

And insurer Munich Re says there were 400 natural catastrophes worldwide in the first six months of 2008 – the most recorded in any single year was 960, in 2007. Some of course are unrelated to the weather — such as the devastating earthquake in Sichuan, China, in May in which 70,000 people died.

It’s of course a stretch to turn such insurance statistics into ’smoking gun’ evidence of global warming caused by human activities. Devastating floods and hurricanes have happened since long before people were burning coal or oil.

Still, most governments say that it makes sense to invest now to try to fix the problem of climate change than wait for consequences that may be a lot worse. Should extreme weather events be a wake-up call for more action?

What do you think?